Rock cutting apparatus



April 24, 1951 J. 5, ROBBINS ROCK CUTTING APPARATUS 3 Sheets-Sheet 1 Filed Aug. 14, 1948 FIG. I

III", II I INVENTOR. $065M? April 1951 J. s. ROBBINS 2,550,202

ROCK CUTTING APPARATUS Filed Aug. 14, 1948 3 Sheets-Sheet 2 4 INVENTOR.

Js zev f @55/4 9 April J. s. ROBBINS 2,550,202

7 ROCK CUTTING APPARATUS Filed Aug. 14, 1948 s Sheets-Sheet s JNVENTOR. Ma /v5 6. Base/Mr Patented Apr. 24, 1951 UNITED STATES PATENT OFFICEAUQU;

ROCK CUTTING APPARATUS James S. Robbins, Highland Park, Ill. 7

Application August 14, 1948, Serial 'No. 44,341

4 claims.

kerfs in frangible rocks of the nature of coal and breaking down the intervening masses, and has reference more particularly to tunneling operations in veins of coal.

The main objects of the invention are to provideimproved rock cutting tools designed to reduce to a minimum the wear and replacement of the kerf cutting devices, to reduce to a minimum the amount of material that is pulverized in the operation of cutting kerfs, and to provide an improved formof rock-cutting roller disk that performs both the operations of forming the kerfs and of breaking down the masses of rock that occupy the spaces between kerfs in a manner that will recover the maximum amount of commercially valuable coal.

- The invention is applicable to various types of rock-cutting mechanism. In the accompanying drawings illustrative embodiments of the invention are shown as applied to a coal-tunneling apparatus of the general type shown, for example, in the McKinlay Patent No. 1,603,621 issued October 19, 1926.

Figure 1 of the drawing is a front view of a mining machine equipped with kerf-cutting devices in accordance with the present invention. 6 Fig. 2 is an elevation showing the'general arrangement of kerfs that are cut in the rock wall at the inner end of a tunnel by a machine of the type shown in Fig. 1.

Fig. .3 is a front view of one of the rotating cutter carrier arms equipped with the improved form of cutters.

Fig. 4 is a side elevation of the same with the contour ofthe rock mass upon which it is operating indicated in section on the plane of the line 4-4 of Fig. '1. There is also included in'this view a fragmentary sectional representation of the chain type of cutter that is used for leveling off the roof and floor surfaces of the tunnel between the paths of the rotating cutter-carrying arms.

1 Fig. 5, is a fragmentary detail, partly in elevation and partly in section, showing one of the cutter disks in its relation to the kerf that it cuts in the rock.

Fig. 6 is a similar detail of a modified form of the cutter roller that is employed at the outer end of the rotating carrier arms of the machine.

Fig. 7 is a perspective view of a portion of a cutter chain equipped with cutter rollers in accordance with the present invention, some of the links of the chain being shown in their assem bled relation to each other and others being separated to disclose the formation of the individual chain links.

Fig. 8 is a sectional detail of the cutter roller as employed on the chain; and

Fig. 9 is a detail of the wedge roller that is employed for splitting the ridge that is formed on the rock face between parallel kerfs that are cu by the rollers of the chain. As represented in Fig. l, the tunneling machinecomprises a frame I0 mountedon wheels I I so as to travel in the direction from which Fig. 1 is viewed. The power supplying equipment, which isnot part of the present invention and is accordingly omitted from the drawing, is carried on the'frame. l0 and includes means for causing the machine to progress toward the leftof Fig. 4 and for the purposes of this disclosure. all such mechanism is assumed to be represented diagrammatically by the frame [0. i

A pair. of parallel horizontal power shafts or spindles l2,journa1ed in bearings l3 on the frame l0, extend outwardly from the front of .the frame I0 and carry drill bits [4 at their forward ends. Each of the spindles l2 also has mounted thereon a cutter-carrying head I5 comprising oppositely extendingradial. arms [6 and I1 equipped with brackets IB on which are journaled a plurality of radially spaced cutter disks designated by numerals l9 to 28, inclusive. The axes of these disks are. generally radial with. respect to. the spindle l2 and inclined forwardly and inwardly with respect to said'axis of the spindle [2.

- The cutter disksron the arm l6 are staggered in their radial distances from the axis of shaft I2 with respect to those on the arm I! so that each disk except the outermost pair will cut a kerf separate from the kerfs cut by the other disks. p The spacing between the shafts I2 is such that the arms l6 and" of the cutter heads can rotate freely between them and the shafts lZjare interconnected by gearing, not shown, so that when they rotate in the direction of the respective arrows 29 and"30 at the same speed, their re-' spective arms will pass clear of each other as will be apparent from Fig. 1. The disks l9 to 28 inclusive have appropriate tooth formations 3| at theirmarginal edges and are journaled so as to rotate freely about their shafts 32. as they roll on the rock face during the rotation of the carrier heads l5. This coupled with the forward progress of the machine re sults, with respectto each carrier head I5, in the cuttingof a bore 33 by the drill bit l4 surrounded by an annular series ofconcentric kerfs and 35, the kerfs 34 being cut by the rollers on the arm l6 and the kerfs 35 being cut by the cutter disks on the arm [1.

In order to reduce to a minimum the width of the kerfs cut by the rotating disks, the thickness of the marginal rim of each of the cutter disks is made as thin as is consistent with durability of the tooth formations thereon, and the face of the disk which is radially inward with respect to. the shaft I2 is dished concavely as indicated at 36 in Figs. 5 and 6 so that the cutting edge 3i of the disk can penetrate for a considerable distance into the face of the rock without interference with the convexly curved I of kerfs that are spaced apart in concentric relation to the bores 33; the alternate kerfs 34 and 35.; respectively. are cut by. cutter disks on the; arms l6 and I! of each rotating cutter head. 1 and the ken-Is. formed by one cutter head. overlap those formed by the other in the space between the boresv 33.

. By tilting the. axesof the cutter disksas shown, the paths of the cutting edges of the teeth on the rims of the cutter disks correspond very closely to the cylindrical wall curvature. at the sides. of thecircular kerfs. 34 and 35, if the diameters. ofv the cutter disksare. properly proportioned with respect, tov their location on the rotating carrier arms and to the angle of. inclination of the axes of rotation of thedisks.

To this end body. faces of the cutter disks, on

the side toward the. center of curvature. of the kerfs, as indicated. at 3B in Figs. 5 and 6, are concavely dished so as to clear the convexly curved side wall 3:! of the kerf throughout a considerable range. of penetration of the cutter disk into. the rock face before the surface. 36. exerts anylateral pressureon the wall. 3]. a As will. be. seen. from Figs. 5 and 6, the. tooth prong, indicated by the numeral 38; in its'rotation about the shaft 32 describes an arc in. the plane represented by the line 39. The: machine moves forward. in. the direction ofthe. arrow 40 as the cutting. of: the kerfproceeds.

Underthe combined action of the. rotation of the cutting disk around the axis of the. shaft [2 and the free. rolling. of the cutter disk around its own axis as it penetrates the-rock, the resultant path of the. cutting. edges of the teeth 38- will conform to thesurface of a cylinderconcentric with the axis of the shaft l-2,andthe kerf that is cut by the teeth 3I- will be substantially uniform in-width up to the depth of penetration at which the inclined arc of travel of the rim of the cutter begins to deviate from the cylindrical wall surface of the kerf.

. The face 4| of the body of the cutter disk is shaped so that after a certain amount of pens-- tration of the rim of the disk into the rock, this fac 41 will presenta conicalshoulder that bears wedgingly against the .rib of rock. that lies; be.- tween the surface 4| and the next outwardly adiacent kerf so as to break down that ribof rock,- asis indicatedby cracks 42, 43 and 44in Figs. 5 6. Similarly the-face 36 of the disk also be gins. to; exert awedging. pressure on its sideof the kerf on further penetration. The side walls of; the disks are highly finished. so that their efj-. tectjs that of a. smooth. gad orwedge, tending fiqbl'e kzqfila i elchunks of rock; asdistinguished 4 from a hammering efiect of roughness that tends to chip the rock.

The outermost disks 21 and 28 travel in the same kerf 45 which .defines in part the inner wall surface contour of the tunnel, as will be understood from Fig. 2 and because of space limitations these outer disks are of somewhat difierent form from the others.

In. order to provide level floor and roof surfaces for the tunnel and cutaway the triangular ridges that are defined bythe paths ofthe cutters on the rotating carrier arms, the machine is equipped with cutter chains and bars, indicated generally by the numeral 46 and located immediately behind the cutter heads l5. These are carried by appropriately located sprockets and guide members so. to travel in endless paths defining the roof and floor of the tunnel. These chains are: equipped with roller disks 4! spaced for cutting parallel kerfs 48 and 49 and with rollers 50 whi zlrtravel paths, midwaybe w eh kerfs cutv by the. d sks 415;! as 0.-: split. and br ak down the ri of: material that. lies between. the: ker 8 n 9.

is cutter cha n is. made. up of links 51 ca ying bearings 52 for the shaftsv of the. cutting disks 41... a ternating. with 1inks53. hav ac a s 54 on which are; ioumaled, th ol rs. B.- In this form of. chain cutter. reliance is h d p rollers 50; for splitting, the: ribv or coal between the, kerfs 481-49. but it will. e. app r n h t nical. ho v surfaces 55.. 0. the cu ting isk and corresp ndin tQ he. wedein u f es. M. of the. cuttin disks .9.: t 2.8. may be pr v ded n th ut in rollers 41 0f; the. carr er ha in wh h case. the. sep r te plitt n rollers-5.0 mi be omitted.-

In operation, machines of this. type, are driven p qsr ssivelyf rwar toitard the. direction from which Fig-.1; isviewed by-appronriatemeans, such. siacks pressin a ainst shoulderscut, in the side. walls. of thev tunnel. The. shafts. t2: and. drill, bits M. are rotatedinopposite directions as indicated by the arrows 29 and. 30;.- sothat. they will have a tendency to carry the broken-down coal toward the center linecf the tunnelwhere it is gathered by=.a. scoop.- 56; leading to; a; conveyor 51 which. carries. it. toward. therear of the machine.

The drill bits L4, extend somewhat. in. advance of the cutting edges ofithe. rollers 19 to. 28. and

. serveto steady thershafts l2. and guide the for.

' ward progress of the machine. The. roller disks,

riding on the facelof the coal-or rock, roll on. their axes so as. to bringtheir peripheral teeth successively into cutting position. Each. roller cuts. a. kerfi in the face ofsthev rock that. is. concentric with the shaft. lZon. which. itscarrier arm it or I cutter teetlr aboutzthe axis of the cutter disk also conformsvery clo'sely to the same cylindrical sur faces within a normalrange of penetration into the kerf. The dished face Siizofathe cutter disk arches; around that portionofj thev convex inner sidewall; ofia kerf that is: subtended by. the circular path. of. the edges. 38: of the. cutting teeth,

as; will be understood. from Figs. 5. and,6;. This condition prevails, throughout; a very.- substantial, degree; of-. -penetratlon of: the disk into. the rock.

face. without; any cutting; awayof the. cylindrical;

7 side walls of the kerf as teeth enter and leave the same in their rotation around the; axis of thecutter disk. i

:The outer corners 38 and 38.] travel paths that areparallel in planes which are indicated in projection in Fig. by the lines 39 and 39.! but due to the cylindrical curvature of the kerf these paths conform to the cylindrical walls of the kerf.

The size and form of each cutter disk depends upon its radial distance from the axis of rotation of its carrier arm and the depth of its desired penetration into the rock face before its wedging shoulder exerts pressure to break down the side wall of the kerf. The angular inclination of the plane of the cutting rim of the disk is selected so that the part of the rims path about its own axis that lies within the kerf will conform substantially with hollow cylinder defined by the walls of the kerf. Theoretically, these conditions seem to call for a special design of each disk according to its location, but in practical application like disks can be employed in different locations by using diifering angular dispositions for their axes without appreciable deviation from the cylindrical wall form of the kerf.

The marginal and body portions of each cutting disk are shaped for a considerable distance inward of its marginal edge so as to clearthe side walls of the cylindrical kerf for a certain desired depth of penetration into the rock wall and then the faces I l and 26 of the body of the cutter disk take on a changing conical form such as to present wedging shoulders bearing against the walls of the kerf so as to break down the material that lies between the respective kerf and the next adjacent one.

Due to the fact that there are many teeth around the periphery of the cutting disks and that in their rolling operation these teeth are subjected to much less strain than that to which the rigid teeth on the carrier arms on former machines are subjected, the cutting tools according to the present invention have a much longer life and less frequent need for replacement. These rotating teeth are also subject to much less abrasive action than are the teeth of rigid cutters.

For like reasons, this construction permits the use of thinner kerf cutting teeth, so as to cut narrower kerfs and consequently results in a substantial reduction of the amount of pulverized coal which has little commercial value;

The conical bodies 4| of the cutting disks tend,

to break off large lumps of coal as indicated by the fracture lines 43 and 44 in Fig. 5. Due to the staggered arrangement of the cutting disks on the opposite arms of the carrier heads, the pressure exerted by the conical shoulder of each cutting disk is directed toward an open portion of an adjacent kerf as is shown in Fig. 4.

The combined effect of the kerf cutting and fragmentation of the intervening ribs of coal enables the machine to progress continuously forward. The cutter bars with the chain cutters follow closely behind the rotary arms and serve to level off the ridges that are left at the roof and floor of the tunnel between the paths of the rotating arms.

Although but one specific embodiment of this invention is herein shown and described, it will be understood that numerous details of the structure shown may be altered or omitted without departing from the spirit of the invention as defined by the following claims.

inner and outer Iclaim:

1. A rockcutti g device, comprising a drilling spindle, means for progressing said spindle axially toward a rock face, a carrier head rotatable about the axis of said spindle, a plurality of kerf cutting disks journaled on said carrier head on axes radially disposed with respect to the axis of said spindle, but inclined toward the drilling end of said spindle, said disks being relatively spaced at different distances from the axis of said spindle for cutting concentric circular kerfs in the rock face as said spindle progresses, and each of said kerf cutting disks having a toothed marginal rim shaped to cut a kerf of substantially uniform width for a relatively large depth of its cut, having its body portion dished concavely on its face that is toward the axis of rotation of the spindle. and having its face that is away from the lastnamed axis bulged convexly to form a conical shoulder spaced inward from its cutting rim so as to bear wedgingly against the outer side of its kerf to break down the rock material between kerfs.

2. Arock cutting device, comprising a drilling spindle, means for progressing said spindle axially toward a rock face, a carrier head rotatable about the axis of said spindle, a plurality of kerf cutting disks journaled on said carrier head on axes radially disposed with respect to the axis of said spindle, but inclined toward the drilling end of said spindle, said disks being relatively spaced at different distances from the axis of said spindle for cutting concentric circular kerfs in the rock face as said spindle progresses, and each of said kerf cutting disks having a toothed marginal rim shaped to cut akerf of substantially uniform width for a relatively large depth of its out, having its body portion dished concaveiy on its face that is toward the axis of rotation of the spindle so as to clear, for said relatively large depth of cut, the subtended part of the convexly curved side of its kerf, and having its face that is away from the last-named axis bulged convexly to form a conical shoulder spaced inward from its cutting rim so as to bear wedgingly against the outer side of its kerf to break down the rock material between kerfs.

3. In a rock cutting device, a rolling cutter disk having a relatively thin toothed rim portion shaped for cutting a narrow kerf of substantial depth in a rock face, and having a radially wedge-shaped body tapering toward said rim, one side of said body being radially dished inward beyond the plane of said rim, and the other side of said body being radially bulged outward from the plane of said rim.

4. A rock cutter, comprising a carrier member, means for driving said carrier member in a progressing direction, means for rotating said carrier member in a plane transverse to said progressing direction, a rotary cutter disk journaled on an axis transverse to both said directions of movement of said carrier member, said cutter disk having a toothed rim portion shaped to cut a kerf of uniform width for a substantial depth into an opposed rock face without wedging pressure on the side walls of such kerf, said cutter disk having a radially wedge-shaped body tapering toward said rim, one side of said body being radially dished inward beyond the plane of said rim, and the other side of said body being radially bulged outward from the plane of said rim.

JAMES S. ROBBINS.

(References on following page) 7 REFERENCES CITED Number- The following references are of recordv in the 503,621 file of'fihis patent: UNITED STATES PATENTS 3 6 1 a Number Name Date 9 10325 Kuhn Sept. 20, 1910 1,204,151 Hughes Nov. 7, 19 16 Number 1", 1'5'3'520 Carlson when- May 1,. 1923 2 Name Date McKinley- Oct. 19; 1926 McKinlay Sept'. 3-, 1929 Gault Sept. 2'7, 1932 Scott May 16, 1933 FOREIGN PATENTS Country Date Germany 1907 

